Takahiro Shikine opened the scoring against Italy's Tommaso Marini, and Kazuki Iimura, who finished fourth in the individual event on Monday, delivered the final touches in a 45-36 win.
The bout was tight, with Japan leading at first, then Italy, until Iimura scored seven decisive touches against Filippo Macchi, silver medallist in the individual event.
Then substitute Yudai Nagano who fenced a flawless round, scored five touches against Italy's Alessio Foconi to give Japan a comfortable lead of six touches.
It was Japan's fifth fencing medal in Paris, and their eighth medal overall in Olympic fencing.
They won the silver medal in the same event at the London Games in 2012.
Japan's foil coaches, Frenchmen Erwann Le Pechoux and Franck Boidin, said earlier in the day that the country had a successful strategy to foster fencing talents, bringing in expertise from abroad in recent years.
Italy took silver for the fifth time in this event, and France claimed bronze.
